Electrical indicating device



1967 E. K. FITCH, JR., ETAL 3,300,776

ELECTRICAL INDICATING DEVI CE Filed July 17, 1964 f m //%w, I. fzwzgwyv IN YEN TORS United States Patent 3,300,776 ELECTRICAL INDICATING DEVICE Eugene K. Fitch, Jr., Charlottesville, and Willis L. Eheart, Jr., Barboursville, Va., assiguors, by mesne assignments, to Teledyne, Incorporated, Hawthorne, Calif. Filed July 17, 1964, Ser. No. 383,452 1 Claim. (Cl. 340373) This invention relates to indicators and especially to an electrical indicator to show when a circuit is energized. This invention constitutes an improvement over the indicator disclosed in US. Patent No. 2,996,705 assigned to Specialties, Inc.

There are many possible applications for a simple, reliable indicator to show when current is flowing in a circuit, both for commercial and military use. The present invention is an improvement over the device described in the above patent in that it provides snap action in two directions whereas the prior device could stop in intermediate positions.

It is an object to provide an indicator of rugged and simple construction and which will provide snap action for both OFF and ON positions.

Another object is to provide an electrical indicator having a magnetized frame for yieldingly holding the rotor in either of two positions and without current in either winding.

A further object is to provide an electrical indicator having a permanent magnet rotor element and two windings, for producing rotation of the rotor in either of two directions, according to which winding is energized.

In the drawings:

FIGURE 1 is a front elevation of our improved electrical indicator.

FIGURE 2 is a top sectional view of the device of FIGURE 1, the section being made by a plane passing through the center of the device and perpendicular to the axis, as indicated by plane AA.

FIGURE 3 is an inside plan view of the cap for the cylindrical casing of the device shown in FIGURE 1.

FIGURE 4 is a cross sectional view of FIGURE 2, in effect a longitudinal cut away of FIGURE 1.

The cylindrical container or casing 1 is made for transparent plastic, glass, or the equivalent and cap 2 having shoulder 3 is pressed into the casing or it may be cemented in leak-proof manner. Rotor 4 is preferably made of plastic and it has projecting axial stub shafts 5 which may be of inserted metal or the shafts may be formed of the rotor material. Permanent magnet 6 is imbedded in the rotor in crosswise manner as indicated in FIGURE 2 and preferably near the central plane of the rotor. Cap 2 has cylindrical recess 7 into which one of the shafts 5 is rotatably fitted. The bottom shaft 5 loosely fits into a similar axial recess in the bottom of casing member 1. Therefore when the cap 2 is properly inserted in the easing the rotor is free to rotate through an angle which is determined by the arcuate length of groove or recess 8 formed or cut into the inner surface of cap 2. Pin 9 is fastened in rotor 4 and moves in groove 8 limiting rotation of the rotor. The rotor movement may be of any practicable displacement but in this case the desired angular movement is approximately ninety degrees.

The cap 2 and the bottom of casing 1 have exterior cross slots in which magnetizing windings 10 and 11 are placed. Soft iron or similar frame 12 having axially aligned bars 13a, 13b, 13c and 13d is placed over container 1 and may be held in position by the windings or by cement. This frame may be made of any suitable easily demagnetized material having good permeability.

The space between rotor 4 and easing 1 is filled with liquid 14 which may be a silicone or other liquid which is effective over a wide range of temperatures. This liquid completely surrounds the rotor and serves to damp movements of the rotor. Any suitable marking such as ON, or OFF as indicated, may carried by the rotor. Colors may also be employed to indicate the two conditions.

In use, the cap is sealed with pin 9 at one end of slot 8 and with magnet 6 attracted to two of the legs 13a and 13b as shown in FIGURE 2. Now if winding 10 is sup plied with current in the proper direction the direction of the magnetic field will be such that magnet 6 and rotor 4 will be flipped around in counter clockwise direction until the poles of the magnet are magnetically attracted to legs or bars and 13d of frame 12. The movement will be sudden or as a snap action and the liquid 14 will cause quick damping of the rotor oscillations which are hardly visible. When it is desired to move the magnet 6 and rotor 4 back to the position shown in FIGURE 2, current is supplied to winding 11 in a direction to reverse the magnetic field so that the rotor snaps back to the position shown.

It is clear that one winding could be used and the direction of current could be reversed in that winding, in order to cause reversal of movement of the rotor. In some applications, however, it is desirable to use two windings rather than to reverse the current.

Important advantages of our device over prior signal indicators are that quick, snap-action is provided and the rotor is magnetically locked for both positions. This prevents oscillation or shifting of the rotor under vibration or similar conditions. Another very desirable advantage of our construction as compared to prior devices is that the rotor is magnetically held in either of the two positions, even though there be no current in either winding. The rotor included in the device described in Patent No. 2,996,705 was held in one position only when the winding was energized.

It is possible to use various plastics in our device such as methyl methacrylate, polycarbonate, or others which are sufliciently transparent, at least for the casing.

What we claim is:

In an indicating device, a cylindrical casing having at least a transparent window therein, a cylindrical rotor within said casing coaxial therewith and mounted for retation through a limited angle, a bar magnet in said rotor aligned generally at right angles to the axis thereof and having its poles adjacent opposite peripheral areas of said rotor, a unitary magnetizable frame surrounding said casing and comprising two spaced end bands coaxial with said rotor and including four members parallel with said axis and joining said end bands, the center lines of said joining members being spaced ninety degrees apart circumferentially, and two adjacent generally rectangular electrical windings surrounding said frame and having a common axis substantially at right angles to the axis of said rotor and casing.

References Cited by the Examiner UNITED STATES PATENTS 2,740,955 4/1956 Barrett 40-28 2,996,705 8/1961 Doty 340373 3,118,138 l/1964 Milas et a1. 340378 3,162,849 12/ 1964 Cunnien 340373 NEIL C. READ, Primary Examiner.

I. J. LEVIN, Assistant Examiner. 

